At least twenty people were wounded, two seriously, when a explosive device detonated on an Israeli bus Monday evening in Jerusalem.

Israel’s security service later confirmed that the explosion was a terror attack. This is the first bombing attack in Jerusalem since the end of the second Intifada in 2005,Haaretz reported.

The blast took place at around 5.50 p.m. on Moshe Baram street, near Hebron road.

Jerusalem Police spokesperson, Asi Aharoni, said the bomb exploded in the back of the bus No.12, which then caused a fire to spread to a private vehicle and a nearby bus that was empty at the time. Most of those injured by the explosion were passengers on the No.12 bus.

Investigations have been launched into the cause of the explosion while forensics and bomb disposal expert confirmed that it was caused by an explosive device, Israeli Police Foreign Press spokesman Micky Rosenfeld said on Twitter.

Those wounded by the blast were later evacuated by Israeli medics Magen David Adom to Shaare Zedek Medical Center and Hadassah University Hospital.

At least seven among them are in moderate-to-serious condition while others were treated for light wounds.

Jerusalem Mayor Nir Barak quickly condemned the blast as a "terror attack", while Israeli Prime Minister Benjamin Netanyahu vowed to "reach the perpetrators and those who support them, and ensure those who stand behind it are held accountable."

Many politicians and Palestinian political factions have also responded to the incident.

Joint Arab List leader Ayman Odeh denounced the attack,writing on social media that, "harming civilians is unacceptable and it also damages the justified Palestinian campaign to end the occupation."

"The Netanyahu government fuels the bloodshed and is fueled by it," he added. "Only a diplomatic solution will bring security for both [Israeli and Palestinian] peoples."

Although no group claimed responsibility for the attack, Palestinian militant groups hailed the bus bombing.

In apublic statement, Hamas spokesman Sami Abu Suhri called the attack a, "natural response to Israeli crimes, notably executions and the desecration of the al-Aqsa Mosque."

Islamic Jihad said the explosion sent a "strong message" that the Palestinian uprising was ongoing, and welcomed the attack as "proof of the failure of security coordination" between Israel and the Palestine Authority.

Gaza-based Popular Resistance Movement leader Haitham al-Ashqar said that the attack was a "natural and rightful response" to continuous Israeli violations against Palestinians and called for more "heroic operations that hurt the occupation and its settlers."

The Jerusalem bus blast took place a few days before the upcoming Jewish holiday of Passover. Following the incident, Israeli forces and border police were deployed across the city to ensure security.